The invention relates to a wiper blade for cleaning a windshield, in particular, a curved windshield of a vehicle.
A wiper blade with a claw of this type has been known for a long time, from U.S. Pat. No. 1,197,338, for example, and finds an application in almost every windshield wiper installation used today for cleaning a windshield on a vehicle. The wiper element of a wiper blade of this type is positioned in the claws with at least limited axial freedom so that the flexible wiper element is largely able to conform to the surface shape of the windshield to be wiped. The claws located on a claw bow serve to guide the wiper element along the windshield to be wiped and to transmit the requisite contact pressure to the wiper element, where the glass can also have a contoured shape. When designing claws, one consideration is that they guide the wiper element, or its rear body, as closely and precisely as possible. Nevertheless, the wiper element must have enough play in the claw to allow the wiper element some axial freedom in the claw.
Known wiper blades of this type however are under the disadvantage that they are poorly suited for use on at least partially contoured windshields.
The conflicting goal of ensuring close and precise guidance of the wiper element in the claw on the one hand and of permitting sufficient play in the claw for axial freedom of the wiper element on the other hand when wiping a contoured windshield cannot be met with known wiper blades. When claws for known windshield wipers are used for glass that is steeply contoured, particularly at the edges of the glass, the wiper element either jams because of its curvature or it floats because of excessive play in the claw so that optimal guiding of the wiper element is not ensured. The consequence is unsatisfactory wiping.
The object of the present invention is therefore to create a wiper blade with claws to locate a rubber-like wiper element at least partially, where the claws ensure good guidance and good axial freedom of the rubber-like wiper element in the claws even with a contoured or partially contoured windshield.
To accomplish this object a wiper blade of the type described above is proposed in which the claw fingers of at least one claw on the wiper blade are offset toward the pivot of the bow in the longitudinal direction of the frame in relation to the contact surface in the claw base in such a way that the outer edges of the claw fingers are located within an area which extends from inclusive of the half of the maximum length of the contact surface as far as the distance between the inner edge of the contact surface and the pivot of the bow. In the sense of the invention, an outer edge of the contact surface in the claw base or an outer edge of a claw foot is always that edge which faces outward in the longitudinal direction of the frame. Correspondingly, an inner edge of the contact surface in the claw base or an inner edge of a claw finger is always that edge which faces inward in the longitudinal direction of the bow.
Alternatively this can be expressed in this way, that in the case of at least one claw on the windshield wiper, the claw fingers projected onto the windshield in relation to the contact surface projected onto the windshield are offset in such a way toward the pivot of the claw bow that the claw fingers projected onto the windshield are not overlapped by the bearing surface projected onto the windshield in the longitudinal direction of the claw bow, or at most by the half of the contact surface facing the pivot projected onto the windshield.
The claw designed under the invention can be used in a wide variety of frame or bow designs. So a claw bow configured according to the invention can, for example, be a primary bow pivotable directly at the wiper arm with a claw at each end, or a claw bow pivoted at a higher order bow with a claw at one end, or a bow with a claw at only one end and a claw bow at its other end. Similarly the frame for a windshield wiper can have two bows which are connected to each other at one of their ends by means of an articulated link and at least one of these bows has at its other end a claw configured in accordance with the invention. The invention is intended further to include wiper blades with such frame or bow designs in which the claw or claws respectively are not located on the underside of the bow, but are located or configured, for example, laterally on or laterally from the bow.
Furthermore it should be made clear that wiper blades in accordance with the invention can be used for all possible types of glass, such as windshields, rear windows, side windows, (viewing windows in general), headlamp glass, rear lamp glass, backup lights and similar lights on different vehicles, specifically motor vehicles.
The wiper blade in accordance with the invention has the advantage that even with more steeply contoured windshields better conformance and guidance of the rubber-like wiper element to the glass to be wiped is ensured compared with known wiper blades. Jamming of the wiper element in the claw, as is regularly the case under the prior art in the case of steeply contoured glass, cannot happen under the invention.
Optimal design of the wiper blade is achieved from a further development of the invention, according to which a clearance d, with d equal to or greater than zero, is present between the inner edge of the contact surface provided on the claw base and the outer edges of the claw fingers.
The relevant cross section for the wiper element is calculated from the width b of the claw and the relevant opening dimension c of the claw for the part of the wiper element received by the claw. The opening dimension c is determined as the hypotenuse of the triangle with the legs as clearance d and claw depth a. From this it follows that when d is greater than or equal to zero, the opening dimension c is greater than or equal to claw depth a. Consequently, it is ensured that the relevant cross section of the claw for the part of the wiper element received by the claw is always greater than or equal to claw height a under the invention, particularly in the case of contoured glass. As a result of the necessary latitude of the wiper element in the claw, axial freedom of the wiper element is always possible and jamming of the wiper element does not occur, whereby correspondingly good results are achieved when wiping the glass.
In accordance with an advantageous embodiment of the invention, the two claw fingers should be aligned with one another in a side view of the wiper blade, or the distance d should be equal in the case of both claw fingers. This enables consistent guidance and transmission of force from the wiper element to the glass.
In an embodiment of the invention, one claw finger is positioned offset in the longitudinal direction of the bow in relation to the other claw finger, or the distance d1 of one claw finger is different from the distance d2 of the other claw finger. Asymmetry of this kind in the claw can be advantageous, particularly with corresponding windshield and/or wiper blade geometries.
A further development of the invention provides for the wiper element to be curved in plan view and for the distance d1 of the claw finger on the claw sidewall which is on the outside of the curvature of the wiper element to be smaller than the distance d2 on the other side of the claw which lies on the inside of the curvature of the wiper element. A further development of the invention of this type has the particular advantage that not only is optimal conformance of the wiper element to a sharply contoured glass ensured but also that when a wiper blade curved in plan view is used, the claw is configured in such a way that the wiper element is not impeded-in its axial freedom by the claw. Wiper blades curved in plan view are used predominantly for stylistic and aesthetic reasons in motor vehicles.
According to another embodiment of the invention, the distances d1 and d2 are dependent on the degree of curvature of the wiper element when seen in plan view. With wiper elements which are only slightly curved, for example, the difference between the distances d1 and d2 is less than with especially sharply curved wiper elements. In this way optimal axial freedom of the wiper elements can be ensured even in the case of wiper elements that are curved in plan view.
One version of the invention envisions that the side of the claw base facing the wiper element with respect to the claw fingers and/or the claw fingers with respect to the claw base has or have a convex curve. Curvatures of this type make it possible to improve the axial freedom of the wiper element, particularly in the case of windshields with widely differing contours.
A further development of the invention provides for at least one claw on the claw bow to be an end claw for the wiper blade. An end claw is that claw on a wiper blade which is closest to the outer glass edge. Vehicle windshields are mostly more steeply contoured specifically in this area than in the center of the windshield. Consequently it makes sense to use claws in this particular area which ensure optimal guidance and transmission of force from the wiper element to the particularly steeply contoured sections of the windshield.